Motion sickness is a condition produced by road, sea, air, or space travel, or by interacting with virtual environments. It is caused by the effect of any pronounced movement on the organ of balance in the inner ear or by sensory conflict about body motion as perceived by different receptors (visual, vestibular, and body proprioceptors). Symptoms may include headache, excessive sweating and salivation, loss of appetite, malaise, nausea, vomiting, gastrointestinal disturbances and fatigue. Vertigo is the illusion that one""s surroundings or self are spinning, either horizontally or vertically, resulting from a disturbance of the semicircular canals in the inner ear or nerve tracts leading from them. It can be induced by motion, zero gravity or disease, and may be accompanied by vomiting, ringing in the ears and unsteadiness.
Travel related motion sickness is experienced by approximately 1% of air travelers and can be as high as 100% of ocean travelers on heavy seas. Children between the ages of 3 and 12 are the most susceptible. 50% of astronauts experience xe2x80x9cspace motion sicknessxe2x80x9d during space travel. While a source of discomfort, motion sickness and vertigo can also result in impaired performance by crew members on ships, planes or spacecraft, by drivers suffering from circulatory ailments, or by users of computer-based virtual environments.
Currently available drugs to treat motion sickness and vertigo produce a variety of undesirable side effects, some producing drowsiness, blurred vision, impaired reaction time and pattern recognition, others negatively affecting mood and sleep.
The genes that play important roles in the proper functioning of the vestibular system remain largely uncharacterized. Identification of such genes can provide methods for screening individuals with genetic susceptibility to motion sickness or vertigo and can also provide targets for developing new therapeutic agents that specifically modulate the expression or activity of genes associated with motion sickness or vertigo. Unfortunately, identification of such genes in mammals can be difficult and time consuming.
Therefore, there is a need to identify drugs that alleviate motion sickness and vertigo without undesirable side effects. There also exists a need to identify genes whose expression or activity is associated with conditions such as motion sickness or vertigo. The present invention satisfies these needs and provides related advantages as well.
The present invention provides a method of identifying a compound that modulates a mammalian vestibular system. The method consists of administering a test compound to an invertebrate, andmeasuring a geotactic behavior of the invertebrate, where a compound that modulates the geotactic behavior of said invertebrate is characterized as a compound that modulates a mammalian vestibular system. The invention also provides a method of identifying a gene that modulates a mammalian vestibular system consisting of obtaining a first and a second strain of an invertebrate; subjecting the first and second invertebrate strains to conditions in which the first strain exhibits a geotactic behavior different than a geotactic behavior exhibited by the second strain; measuring gene expression levels in the first and second strains, and identifying one or more genes that are differentially expressed in the first strain relative to the second strain, whereby a mammalian gene having substantially the same nucleic acid sequence as the one or more differentially expressed genes modulates the mammalian vestibular system.